I am really indebted to Dmytro Mishchenko right now. This week he released a new Telnet SSH client for the BlackBerry PlayBook. This new client is based on PuTTY and supports the SSH, Telnet, and Rlogin protocols. This app is built on the work from PuTTY, qPuTTY, and the QT Library so it has a long legacy to build on. The SSH Client still has a way to go to be the perfect SSH client for the BlackBerry PlayBook but it definitely is the current best option for SSH on the PlayBook.
You can pick up SSH Client for the BlackBerry PlayBook for $1.99 in App World